1. Field of the Invention
The present invention relates to a liquid crystal display device, specifically to a liquid crystal display device of a projection type or a reflection type using no polarizing plates.
2. Description of the Related Art
Well known as conventional liquid crystal display devices are a twist nematic (TN) mode making use of an optical activity, birefringence control (ECB) mode making use of an optical coherence and a super twist nematic (STN) mode. Any mode requires one or two polarizing plates, and this provides the defects that the satisfactory contrasts and viewing angles can not be obtained and the response speeds are slow. A liquid crystal display device having an alternate electrode for the purpose of improving a viewing angle is reported in SID International Symposium Digest of Technical Papers, vol. XXIX, p. 718, (1998). This liquid crystal display device has the defect that the response speed is slow while the viewing angle is wide. Further, a liquid crystal display device having a zigzag electrode is reported in IDW Proceedings of The Fourth International Display Workshops, p. 175, (1997). This liquid crystal display device has a wide viewing angle and a quick response speed but has the defects that the brightness is low and the driving voltage is high.
Either of the birefringence control (ECB) mode and the super twist nematic (STN) mode has had the defect that they have a low contrast and a slow response speed and therefore are unsuitable for animation display. A twist nematic (TN) mode has had the difficulty that the response speed is quick but the viewing angle is very narrow. Either of the twist nematic (TN) mode, the birefringence control (ECB) mode and the super twist nematic (STN) mode requires one or two polarizing plates, and therefore a part of transmitted light or reflected light is absorbed by the polarizing plates. Accordingly, a reduction in the brightness of the display device is brought about, and the contrast thereof is reduced as well. The back light has been strengthened in order to supplement the brightness, which in turn has increased the power consumption. Further, since the birefringence control (ECB) mode and the super twist nematic (STN) mode are colored by birefringence, an optical compensating film is required, and this has been a factor for an increase in the cost in addition to a difficulty in the optical design.